This invention generally relates to novel compounds, pharmaceutical compositions and their use. This invention more specifically relates to novel heterocyclic compounds that bind to chemokine receptors, including CXCR4 and CCR5, and demonstrates protective effects against infection of target cells by a human immunodeficiency virus (HIV).
Approximately 40 human chemokines have been described, that function, at least in part, by modulating a complex and overlapping set of biological activities important for the movement of lymphoid cells and extravasation and tissue infiltration of leukocytes in response to inciting agents (See, for example: P. Ponath, Exp. Opin. Invest. Drugs, 7:1-18, 1998). These chemotactic cytokines, or chemokines, constitute a family of proteins, approximately 8-10 kDa in size. Chemokines appear to share a common structural motif, that consists of 4 conserved cysteines involved in maintaining tertiary structure. There are two major subfamilies of chemokines: the xe2x80x9cCCxe2x80x9d or xcex2-chemokines and the xe2x80x9cCXCxe2x80x9d or xcex1-chemokines. The receptors of these chemokines are classified based upon the chemokine that constitutes the receptor""s natural ligand. Receptors of the xcex2-chemokines are designated xe2x80x9cCCRxe2x80x9d; while those of the xcex1-chemokines are designated xe2x80x9cCXCRxe2x80x9d.
Chemokines are considered to be principal mediators in the initiation and maintenance of inflammation. More specifically, chemokines have been found to play an important role in the regulation of endothelial cell function, including proliferation, migration and differentiation during angiogenesis and re-endothelialization after injury (Gupta et al., J. Biolog. Chem., 7:4282-4287, 1998). Two specific chemokines have been implicated in the etiology of infection by human immunodeficiency virus (HIV).
In most instances, HIV initially binds via its gp120 envelope protein to the CD4 receptor of the target cell. A conformational change appears to take place in the gp120 which results in its subsequent binding to a chemokine receptor, such as CCR-5 (Wyatt et al., Science, 280:1884-1888 (1998)). HIV-1 isolates arising subsequently in the infection bind to the CXCR4 chemokine receptor. In view of the fact that the feline immunodeficiency virus, another related retrovirus, binds to a chemokine receptor without needing to bind first to the CD4 receptor, suggests that chemokine receptors may be the primordial obligate receptors for immunodeficiency retroviruses.
Following the initial binding by HIV to CD4, virus-cell fusion results, which is mediated by members of the chemokine receptor family, with different members serving as fusion cofactors for macrophage-tropic (M-tropic) and T cell line-tropic (T-tropic) isolates of HIV-1 (Carroll et al., Science, 276: 273-276 1997). During the course of infection within a patient, it appears that a majority of HIV particles shift from the M-tropic to the more aggressive T-tropic viral phenotype (Miedema et al., Immune. Rev., 140:35 (1994)) Curiously, the M-tropic viral phenotype correlates with the virus""s ability to enter the cell following binding of the CCR-5 receptor, while the T-tropic viral phenotype correlates with viral entry into the cell following binding and membrane fusion with the CXCR-4 receptor. Clinically observations suggest that patients who possess genetic mutations in the CCR-5 or CXCR4 appear resistant or less susceptible to HIV infection.
However, the binding of chemokine receptors to their natural ligands appears to serve a more evolutionary and central role than only as mediators of HIV infection. The chemokine receptor, CXCR-4 has been found to be essential for the vascularization of the gastrointestinal tract (Tachibana et al., Nature, 393:591-594 (1998)) as well as haematopoiesis and cerebellar development (Zou et al., Nature, 393:591-594 (1998)). Interference with any of these important functions served by the binding of pre-B-cell growth-stimulating factor/stromal derived factor (PBSF/SDF-1) to the CXCR-4 chemokine receptor results in lethal deficiencies in vascular development, haematopoiesis and cardiogenesis. Similarly, fetal cerebellar development appears to rely upon the effective functioning of CXCR-4 in neuronal cell migration and patterning in the central nervous system. This G-protein-coupled chemokine receptor appears to play a critical role in ensuring the necessary patterns of migration of granule cells in the cerebellar anlage.
In attempting to better understand the relationship between chemokines and their receptors, recent experiments to block the binding of HIV to the CXCR4 chemokine receptor were carried out through the use of monoclonal antibodies or small molecules that appear to suggest a useful therapeutic strategy (Schols et al, J. Exp. Med. 186:1383-1388 (1997); Schols et al., Antiviral Research 35:147-156 (1997)). Small molecules, such as bicyclams, appear to specifically interfere with the CXCR4 binding and not CCR-5 binding (Donzella et al, Nature Medicine, 4:72-77 (1998)). These experiments demonstrated interference with HIV entry and membrane fusion into the target cell in vitro. Additional experiments monitoring the calcium flux or Ca2+ mobilization assay demonstrated that a bicyclam also functioned as an antagonist to signal transduction resulting from the binding of stromal derived factor or SDF-1xcex1, the natural chemokine to CXCR4. SDF-1 has been shown to be essential for CXCR4 dependent migration of human stem cell function in non-obese diabetic (NOD) severe combined immunodeficient (SCID) mice (Peled et al, Science 283: 845-848 (1998)). The role of CXCR4 appears critical for migration to SDF-1 and localization of stem cells in bone marrow.
U.S. Pat. No. 5,583,131, U.S. Pat. No. 5,698,546 and U.S. Pat. No. 5,817,807, which are herein incorporated in their entirety by reference, disclose cyclic compounds that are active against HIV-1 and HIV-2 in in vitro tests. It was subsequently discovered and further disclosed in copending application U.S. Ser. No. 09/111,895 that these compounds exhibit anti-HIV activity by binding to the chemokine receptor CXCR4 expressed on the surface of certain cells of the immune system. This competitive binding thereby protects these target cells from infection by HIV which utilize the CXCR4 receptor for entry. In addition, these compounds antagonize the binding, signaling and chemotactic effects of the natural CXC-chemokine for CXCR4, stromal cell-derived factor 1xcex1 (SDF-1).
Additionally we have shown that these cyclic polyamine antiviral agents described in the above-mentioned patents have the effect of enhancing production of white blood cells as well as exhibiting antiviral properties. Thus, these agents are useful for controlling the side-effects of chemotherapy, enhancing the success of bone marrow transplantation, enhancing wound healing and burn treatment, as well as combating bacterial infections in leukemia.
We further disclosed that these novel compounds demonstrate protective effects against HIV infection of target cells by binding in vitro to the CC-5 receptor (CCR-5).
Herein, we disclose novel compounds that exhibit protective effects against HIV infection of target cells by binding to chemokine receptors, including CXCR4 and CCR5, in a similar manner to the previously disclosed macrocyclic compounds. (see Table 1 for comparative examples).
The present invention provides novel compounds that bind chemokine receptors and interfere with the binding of the natural ligand thereto. The compounds of the present invention are useful as agents demonstrating protective effects on target cells from HIV infection. Other embodiments of the present invention are compounds that act as antagonists or agonists of chemokine receptors, which are useful as agents capable of reconstituting the immune system by increasing the level of CD4+ cells; as antagonist agents of apoptosis in immune cells, such as CD8+ cells, and neuronal cells; as antagonist agents of migration of human bone marrow B lineage cells to stromal-derived factor 1, as well as other biological activities related to the ability of these compounds to inhibit the binding of chemokines to their receptors.
Accordingly, the present invention provides a compound of Formula I 
wherein, W is a nitrogen atom and Y is absent or, W is a carbon atom and Yxe2x95x90H;
R1 to R7 may be the same or different and are independently selected from hydrogen or straight, branched or cyclic C1-6 alkyl;
R8 is a substituted heterocyclic group or a substituted aromatic group
Ar is an aromatic or heteroaromatic ring each optionally substituted at single or multiple, non-linking positions with electron-donating or withdrawing groups;
n and nxe2x80x2 are independently, 0-2;
X is a group of the formula: 
Wherein, Ring A is an optionally substituted, saturated or unsaturated 5 or 6-membered ring, and P is an optionally substituted carbon atom, an optionally substituted nitrogen atom, sulfur or oxygen atom. Ring B is an optionally substituted 5 to 7-membered ring. Ring A and Ring B in the above formula can be connected to the group W from any position via the group V, wherein V is a chemical bond, a (CH2)nxe2x80x3 group (where nxe2x80x3=0-2) or a Cxe2x95x90O group. Z is, (1) a hydrogen atom, (2) an optionally substituted C1-6 alkyl group, (3) a C0-6 alkyl group substituted with an optionally substituted aromatic or heterocyclic group, (4) an optionally substituted C0-6 alkylamino or C3-7 cycloalkylamino group, (5) an optionally substituted carbonyl group or sulfonyl.
In the above Formula I, examples of the optionally substituted 5 or 6-membered ring A are benzene, pyridine, pyrimidine, pyrazine, pyridazine, triazine, piperidine, piperazine, imidazole, pyrazole, triazole, oxazole, thiazole. Six-membered rings are preferred for ring A, particularly benzene, pyridine and piperidine.
The invention also provides a compound of Formula I 
In which, W, Y, n, nxe2x80x2, Ar, R1-R8 are defined as above,
X and Z are independently selected from H, optionally substituted C1-6 alkyl or C0-6 alkaryl or C0-6 alkylheterocyclyl groups. The X and Z groups may also bind each other to form an optionally substituted 5- to 7-membered cyclic amine group such as tetrahydropyrrole, pyrrolidine, piperazine, homopiperazine, piperidine, morpholine, thiomorpholine, pyrrole, imidazole etc., or an optionally substituted pyran, thiopyran or cycloalkyl ring or the groups X and Z optionally fused to the group Ar.
The optional substituents are defined herein infra.
One preferred embodiment of the present invention is a pharmaceutical composition comprising a therapeutically effective amount of the compound according to Formula I. Another preferred embodiment of this invention is a method of treating a disease of the human body or the bodies of other mammals comprising the administration of a pharmaceutical composition comprising a therapeutically effective amount of the compound according to Formula I. A still further embodiment of the present invention provides a method for blocking or interfering with the binding by a chemokine receptor with its natural ligand, comprising the contacting of said chemokine receptor with an effective amount of the compound according to Formula I.
This invention may also provide for the use of a compound of Formula I in the manufacture of a medicament for the treatment of a disease in which blocking or interfering with binding of a chemokine receptor with its natural ligand is advantageous, comprising formulating a composition comprising a therapeutically effective amount of the compound of Formula I. It is further contemplated that this invention is also useful for providing a method of protecting target cells possessing chemokine receptors, the binding to which by a pathogenic agent results in disease or pathology, comprising administering to a mammalian subject a pharmaceutical composition comprising a therapeutically effective amount of the compound according to Formula I.
The invention also includes what may be termed as xe2x80x9cpro-drugxe2x80x9d, that is, protected forms of the compounds, which release the compound after administration to a patient. For example, the compound may carry a protective groups which is split off by hydrolysis in body fluids e.g. in the bloodstream, thus releasing active compound or is oxidized or reduced in body fluids to release the compound. A discussion of pro-drugs may be found in xe2x80x9cSmith and Williams"" Introduction to the Principles of Drug Designxe2x80x9d, H. J. Smith, Wright, Second Edition, London 1988.
Acid addition salts, which are pharmaceutically acceptable such as salt with inorganic base, a salt with organic base, a salt with inorganic acid, a salt with organic acid, a salt with basic or acidic amino acid, etc. Examples of the salt with the inorganic base include a salt with alkali metal (e.g. sodium, potassium, etc.), alkaline earth metal (e.g. calcium, magnesium, etc.), aluminum, ammonium, etc. Examples of the salt with the organic base include a salt with trimethylamine, triethylamine, pyridine, picoline, ethanolamine, diethanolamine, triethanolamine, dicyclohexylamine, N,Nxe2x80x2-dibenzylethylenediamine etc. Examples of the salt with the inorganic acid include a salt with hydrochloric acid, hydrobromic acid, nitric acid, sulfuric acid, phosphoric acid, etc. Examples of the salt with the organic acid include a salt with formic acid, oxalic acid, acetic acid, tartaric acid, methanesulfonic acid, benzenesulfonic acid, malic acid, methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, etc. Examples of the salt with the basic amino acid include a salt with arginine, lysine, ornithine, etc. Examples of the salt with the acidic amino acid include a salt with aspartic acid, glutamic acid, etc. Non-toxic in the present tense has to be considered with reference to the prognosis for the infected patient without treatment.
Citation of the above documents is not intended as an admission that any of the foregoing is pertinent prior art. All statements as to the date or representation as to the contents of these documents is based on the information available to the applicants and does not constitute any admission as to the correctness of the dates or contents of these documents. Further, all documents referred to throughout this application are hereby incorporated in their entirety by reference herein.